Answer:
In my opinion, capital punishment is much more humane. When you sentence someone to life in prison, that is far worse than ending their suffering with a quick execution.
That person is forced to live the rest of their life in a tiny, uncomfortable prison cell. Everyday they repeat the same tasks over and over. It is tourture to whoever is sentenced to it, but on the other hand, if they get the electric chair, it's over like that. Much faster, less suffering.